1. Field of the Invention
The present invention relates to a method and apparatus for preloading Enhanced Navigation (ENAV) data required for seamless reproduction of audio/video (AV) data in an improved navigation mode (hereinafter referred to as an ‘ENAV mode’), to a buffer and reproducing the preloaded ENAV data, and an information storage medium thereof.
2. Description of the Related Art
Personal computer (PC)-based digital versatile discs (DVDs), i.e., interactive DVDs, capable of reproducing AV data in an interactive mode have been placed on the market. On an interactive DVD, AV data is recorded according to a general DVD-Video standard and data is further recorded to support an ENAV mode. The AV data recorded on the interactive-DVD can be displayed in two modes: a video mode in which AV data is displayed with the same method of displaying data recorded on a general DVD, and an ENAV mode in which the AV data is reproduced and displayed in a window defined in a markup document. When a user selects the ENAV mode, a browser built in a personal computer (PC) interprets and displays ENAV data recorded on the interactive DVD. In the ENAV mode, a screen is displayed as defined in the markup document and/or an application program while the AV data, which is selected by the user, is included in the screen. A representative example of the ENAV data is the markup document described using a markup language.
If the AV data is a movie title, a movie screen is displayed in a part of a markup screen where the markup document is interpreted and displayed, the movie screen being embedded into the markup screen, and various additional information, such as a script and plot of the movie and photos of related actors and actresses, regarding the movie is displayed in the other part of the markup screen. The additional information includes various resource files such as image files and text files. The displayed markup document enables interaction with the user. For instance, when the user clicks a button in the markup screen, the profile of an actor appearing in the movie screen can be displayed.
However, in the ENAV mode, it is required for a DVD drive installed in the PC to read ENAV data from the interactive DVD and store the ENAV data in a buffer while reading the AV data from the interactive DVD and storing it in the buffer. Accordingly, it is difficult to reproduce the AV data without a pause. That is, seamless reproduction of the AV data is not guaranteed.